Investigations of thermal behaviours of asphalt pavement under short-term preheating technique for pavement overlay construction

Asphalt concrete overlay is typically designed to be thin to minimise maintenance and rehabilitation costs, which makes it challenging to be compacted and may affect its bonding conditions with the existing pavement. The short-term preheating involves swiftly heating the pavement surface before overlay paving commences, aiming to enhance the bonding conditions between the overlay and the existing pavement. Implementing the preheating approach requires a comprehensive understanding of thermal behaviours exhibited by existing pavement under short-term preheating and the factors affecting it. In this research, the feasibility of using electric heating tubes as short-term preheating heat source was analysed, and a finite element (FE) model for analysing the thermal behaviour of asphalt pavements under rapid preheating was developed. The key control parameter between the heat source and the pavement were determined and calibrated by field tests. Further sensitivity analyses of the effects of multiple factors on the thermal response of the pavement during rapid preheating were conducted, and a prediction model of the maximum pavement temperature achievable through preheating was developed. The established prediction model is expected to provide references for implementing short-term preheating in pavement overlay construction.